1 thing is total xp you need to achieve something, but with that you also have to consider how much xp you make
how much xp can 60 lvl mage party pull on c4 in 20 minutes? and how much can same party pull on classic? pretty sure the number is not same and that you gain much more xp in classic, which means its not exactly 3x harder to lvl up on those 2 chronicles even if total xp is 3x higher
removing xp scrolls is minimum what you can do, only xp boost which should ever exist are fishing stews (10%) and clan online bonus (15%?), and those are both 2.0 i believe